Appliance thermal management systems

ABSTRACT

A thermal appliance is provided. The thermal appliance includes a heating compartment inside of an enclosure, with insulation disposed between the heating compartment and enclosure. Retainers or standoffs are also included in the thermal appliance to prevent air gaps from forming between the insulation and the heating compartment, and to prevent the insulation from making contact with the enclosure.

RELATED APPLICATIONS

This patent application is a divisional of U.S. Ser. No. 14/213,456filed Mar. 14, 2014 titled “APPLIANCE THERMAL MANAGEMENT SYSTEMS,” whichclaims the benefit of U.S. Provisional Patent Application Ser. No.61/794,131, filed on Mar. 15, 2013, titled “APPLIANCE THERMAL MANAGEMENTSYSTEMS.” These applications are incorporated herein by reference intheir entirety.

TECHNICAL FIELD

This invention relates generally to thermal management systems forcontrolling the temperature of a heating appliance, such as a thermaloven or a thermal hot water heater, and more specifically relates tocontrolling the temperature of localized “hot spots” within the heatingappliance.

BACKGROUND

Thermal appliances, such as for example ovens and hot water heaters usehigh heat levels for various purposes, including food preparation,self-cleaning, and heating of water. The high heat levels are producedwithin a heating compartment or a heating tank, which is also thelocation of the food being prepared, or the interior surfaces beingself-cleaned, or the water being heated. Various energy sources,including natural gas, electricity, and oil can be used to produce thehigh heat levels. The heating compartment or heating tank is typicallypositioned within a cabinet or a cylindrical enclosure. The cabinet orcylindrical enclosure typically includes side panels, a back panel, atop panel and a bottom panel. High temperature insulation can bepositioned adjacent to the sides, top, back, and bottom of the heatingcompartment or heating tank. The high temperature insulation is used tocontrol the flow of heat from the sides, top, and bottom of the heatingcompartment or heating tank to the outside of the enclosure or cabinet.The temperature within the heating compartment or heating tank duringnormal operation can reach up to 1600 degrees F. (871 degrees C.).

Numerous consumer safety codes have been enacted which relate to themaximum allowable external temperature of the enclosure or cabinet.Since some thermal appliances, such as thermal ovens, are typicallypositioned adjacent other fixtures, such as for example otherappliances, or are built-in next to wood-based cabinets, the enclosureor cabinet can be very close to or in direct contact with these otherfixtures. Additionally, surface temperature limits may be designedaround possible exposure to human touch.

SUMMARY

In a thermal appliance embodying the principles of the invention,retainers or standoffs are used to eliminate the formation of hotspotson the exterior of the appliance enclosure. The appliance includes aheating compartment within the enclosure that is surrounded byinsulation. The retainers or standoffs are positioned between theenclosure and heating compartment to keep the insulation in continuouscontact with the heating compartment such that no air gaps are formedbetween the insulation and the heating compartment. The retainers orstandoffs also prevent the insulation from making contact with theenclosure. By eliminating the air gaps and contact between theinsulation and enclosure, hot spots on the exterior of the enclosure dueto air heated in the gap and contact between the insulation andenclosure are reduced or eliminated.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a thermal oven.

FIG. 2 is a cross-sectional view taken along the plane indicated bylines 2-2 in FIG. 1 illustrating an oven cavity.

FIG. 3 is a cross-sectional view taken along the plane indicated bylines 3-3 in FIG. 1.

FIG. 4 is a perspective view of a thermal oven in a thermal testfixture.

FIG. 5 is a cross-sectional view taken along the plane indicated bylines 5-5 in FIG. 4.

FIG. 6 is a cross-sectional view taken along the plane indicated bylines 6-6 in FIG. 4.

FIGS. 7A and 7B are schematic illustrations showing thermal measurementstaken of the oven shown in FIG. 4.

FIG. 8 is a perspective view of an oven similar to the oven illustratedby FIG. 1 with radiant heat shields.

FIG. 9 is a cross-sectional view taken along the plane indicated bylines 9-9 in FIG. 8.

FIG. 10 is a cross-sectional view taken along the plane indicated bylines 10-10 in FIG. 8.

FIGS. 11A and 11B are schematic illustrations showing thermalmeasurements taken of the oven shown in FIG. 8.

FIG. 12 is a view similar to the view illustrated by FIG. 2 illustratinggaps between insulation and an oven liner.

FIG. 13 is a side elevational sectional view showing the gapsillustrated by FIG. 12.

FIG. 14 is a top elevational sectional view taken along the planeindicated by lines 14-14 in FIG. 1 showing the gaps illustrated by FIG.12.

FIG. 15 is a schematic illustration showing thermal measurements takenof the oven shown in FIGS. 12-14.

FIG. 16 is a view similar to the view illustrated by FIG. 2 illustratinginsulation contact with an outer oven cabinet.

FIG. 17 is a schematic illustration showing thermal measurements takenof the oven shown in FIG. 16.

FIG. 18 is a view similar to the view of FIG. 2 where the oven includesclips that prevent gaps between the insulation and the oven liner andprevents insulation from making contact with the outer oven cabinet.

FIG. 19 is a sectional view taken along the plane indicated by lines19-19 in FIG. 18 showing clips illustrated by FIG. 18.

FIG. 20 is a sectional view taken along the plane indicated by lines20-20 in FIG. 18 showing clips illustrated by FIG. 18.

FIG. 21 is a view similar to FIG. 15 illustrating the effect of theclips shown in FIGS. 18-20.

FIG. 22 is a view similar to FIG. 17 illustrating the effect of theclips shown in FIGS. 18-20.

FIG. 23 is a view similar to FIG. 2 of an oven having a high densityinner insulation layer and a low density outer insulation layer.

FIG. 24 is a view similar to FIG. 3 of an oven having the insulationlayers shown in FIG. 23.

FIG. 25 is a view similar to FIG. 14 of an oven having the insulationlayers shown in FIG. 23.

FIG. 26 is a view of an exemplary embodiment of an oven that is similarto the embodiment illustrated by FIG. 23 where the low density outerinsulation layer is configured to contact the outer oven cabinet.

FIG. 27 is a view similar to FIG. 3 of an oven having the insulationlayers shown in FIG. 26.

FIG. 28 is a view similar to FIG. 25 of an oven having the insulationlayers shown in FIG. 26.

FIG. 29 is a view similar to the view illustrated by FIG. 2 of anexemplary embodiment of an oven with convection airflow managementfeatures.

FIG. 30 is a view similar to FIG. 3 of an oven having the convectionairflow management features of FIG. 29.

FIG. 31 is a perspective view of a thermal oven.

FIG. 32 is a cross-sectional view taken along the plane indicated bylines 32-32 in FIG. 31 illustrating an oven cavity.

FIG. 33 is a cross-sectional view taken along the plane indicated bylines 33-33 in FIG. 31.

FIG. 34 is a schematic illustration showing thermal measurements takenof the oven shown in FIGS. 31-33.

FIG. 35 is a perspective view of an oven similar to the oven illustratedby FIG. 31 with upper oven insulation extensions.

FIG. 36 is a cross-sectional view of the oven illustrated by FIG. 35taken along the plane indicated by lines 33-33 in FIG. 31.

FIG. 37 is a view similar to FIG. 34 illustrating the effect of theinsulation extensions shown in FIG. 35.

FIG. 38 is a view similar to the views of FIG. 18 where the ovenincludes standoffs and retaining elements that prevent gaps between theinsulation and the oven liner and prevent the insulation from makingcontact with the outer over cabinet.

FIG. 39 is a sectional view taken along the plane indicated by lines39-39 in FIG. 38 showing standoffs and retaining elements illustrated byFIG. 38.

FIG. 40 is a sectional view taken along the plane indicated by lines40-40 in FIG. 38 showing standoffs and retaining elements illustrated byFIG. 38.

FIG. 41 is a view similar to the views of FIG. 18 where the ovenincludes “M” or “W” shaped standoffs that prevent gaps between theinsulation and the oven liner and prevent the insulation from makingcontact with the outer over cabinet.

FIG. 42 is a sectional view taken along the plane indicated by lines42-42 in FIG. 41 showing standoffs and retaining elements illustrated byFIG. 41.

FIG. 43 is a sectional view taken along the plane indicated by lines43-43 in FIG. 41 showing standoffs and retaining elements illustrated byFIG. 41.

FIG. 44 is a view similar to the views of FIG. 18 where the ovenincludes “M” or “W” shaped standoffs attached through the insulation tothe oven liner that prevent gaps between the insulation and the ovenliner and prevent the insulation from making contact with the outer overcabinet.

DETAILED DESCRIPTION

The description and drawings disclose a thermal management systems forthermal appliances. A thermal appliance is defined as an apparatus orstructure for heating an object positioned within the appliance. Variousexamples of thermal appliances include traditional residential ovens,commercial ovens, convection ovens, microwave ovens, hot water heatersor any other apparatus or structure sufficient to heat an objectpositioned within the appliance.

Referring now to the drawings, there is shown in FIG. 1 one example of athermal appliance, namely a thermal oven 10. The thermal oven 10includes a substantially flat, top cooking surface 12. A plurality ofheating elements or burners 14 are typically positioned on the topcooking surface 12, although the heating elements or burners 14 areoptional. The thermal oven 10 includes a plurality of controls 26 forthe burners 14 on the cooking surface as well as a control panel 28 forcontrolling the temperature within an oven cavity 16. Typically, thecontrols 26 and control panel 28 are mounted on a backsplash 30. Thebacksplash 30 is located on a back edge of the cooking surface 12. Thebacksplash 30 typically extends away from, and substantiallyperpendicular to, the cooking surface 12.

As shown in FIGS. 1-3, the thermal oven 10 includes a pair of opposedside panels 52 and 54, a back panel 24, a bottom panel 25, and a frontpanel 32. The opposed side panels 52 and 54, back panel 24, bottom panel25, front panel 32 and cooking surface 12 are configured to form anouter oven cabinet 33. The outer oven cabinet 33 is typically finishedwith an aesthetically pleasing finish, such as for example a paintedfinish, a porcelain enamel finish or a brushed stainless steel finish,particularly for those panels that are exposed to view by consumers.

The front panel 32 includes an insulated oven door 18 pivotallyconnected to the front panel 32. The oven door 18 is hinged at a lowerend to the front panel 32 such that the oven door can be pivoted awayfrom the front panel 32 and the oven cavity 16. Optionally, the ovendoor 18 can include a window. The window is typically made of glass, inorder that the user can view the contents of the oven cavity 16 duringits use. Also, the oven door 18 can include a handle 21 configured tofacilitate moving the oven door 18 from an open position to a closedposition and vice versa.

As shown in FIGS. 2 and 3, the outer oven cabinet 33 supports an inneroven liner 15. The inner oven liner 15 includes opposing liner sides 15a and 15 b, a liner top 15 c, a liner bottom 15 d and a liner back 15 e.The opposing liner sides 15 a and 15 b, liner top 15 c, liner bottom 15d, liner back 15 e and oven door 18 are configured to define the ovencavity 16.

As further shown in FIGS. 2 and 3, the exterior of the oven liner 15 iscovered by insulation material 38. A typical insulation material 38 isfiberglass insulation, although other insulation material 38 can beused. In one exemplary embodiment, the insulation material 38 is abinderless or dry binder fiberglass insulation material. For example,the fiberglass insulation material may be any of the insulationmaterials and/or may be formed by any of the processes described in U.S.patent application Ser. No. 13/632,895, titled “METHOD FOR FORMING A WEBFROM FIBROUS MATERIAL,” filed on Oct. 1, 2013 and U.S. patentapplication Ser. No. 13/839,350, titled “METHOD FOR FORMING A WEB FROMFIBROUS MATERIAL,” filed on Mar. 15, 2013, and which is acontinuation-in-part of U.S. patent application Ser. No. 13/632,895,both of which are incorporated herein by reference in their entirety.The insulation material 38 typically has a density within the range fromabout 0.5 lbs/ft.sup.3 (8 kg/m.sup.3) to about 10.0 lbs/ft.sup.3 (160kg/m.sup.3), and a thickness within the range from about 1.0 inches(2.54 cm) to about 3 inches (7.62 cm). In other embodiments, theinsulation material 38 may have a thickness that is less than 1 inch.For example, the insulation may be ¼″ to ¾″ thick. The insulationmaterial 38 is placed in contact with an outside surface of the ovenliner 15.

The insulation material 38 is used for many purposes, includingretaining heat within the oven cavity 16 and limiting the amount of heatthat is transferred from the heated cavity to the exterior of theappliance by conduction, convection and radiation to the outer ovencabinet 33. The thermal insulation systems disclosed by this applicationare composite systems that are multi-dynamic.

As shown in FIGS. 2 and 3, an air gap 36 is formed between theinsulation material 38 and the outer oven cabinet 33. The air gap 36 isused as a further insulator to limit the conductive heat transferbetween oven liner 15 and the outer oven cabinet 33. The use of the airgap 36 supplements the insulation material 38 to minimize the surfacetemperatures on the outer surfaces of the outer oven cabinet 33.

During normal cooking operation, the thermal oven 10 will heat the ovencavity 16 to a cooking temperature range from about 250.degree. F.(121.degree. C.) to about 500.degree. F. (260.degree. C.). Whenoperating in a self-cleaning mode, the thermal oven 10 heats the ovencavity 16 to a temperature in a range from about 750.degree. F.(398.degree. C.) to about 900.degree. F. (482.degree. C.). Forcommercial or industrial thermal ovens, the temperature within the ovencavity 116 can reach as high as 1600.degree. F. (871.degree. C.). Heatexposure tests, such as the UL858 Standard for Household Electric Rangesand ANSI Z21.1 Standard for Household Cooking Gas Appliances, requirethat the maximum allowable surface temperature be 152.degree. F. for apainted metal surface, 160.degree. F. for a porcelain enamel surface, or172.degree. F. for a glass surface. These temperatures are for surfacesthat are visible (i.e. not covered or concealed by cabinetry) afterinstallation of the appliance.

FIGS. 4-6 illustrate an oven 10 positioned within a thermal test fixture410 for the heat exposure tests, such as the UL858 Standard forHousehold Electric Ranges and/or ANSI Z21.1. The test fixture 410includes side walls 452, 454 and a back wall 424 that approximate thespace the oven 10 will be installed in at a residence. The pair ofopposed side panels 52 and 54 and a back panel 24 of the oven are spacedapart from the side walls 452, 454 and a back wall 424 by small gaps552, 554 and 524 respectively. Thermocouples are distributed over thepair of opposed side panels 52 and 54 and a back panel 24 for thermaltesting of the oven 10.

FIGS. 7A and 7B are schematic illustrations showing thermal measurementstaken during a test of the oven 10 in the test fixture 410 of FIGS. 4-6.FIG. 7A illustrates thermal measurements of a right side of the oven andFIG. 7B illustrates thermal measurements of a left side of the oven.Shaded areas 710 represents hot spots at upper front corners 720 (SeeFIG. 4) and shaded areas 712 represent hot spots at rear upper corners722 (See FIGS. 4 and 6) of the oven during thermal testing in thefixture 410.

FIG. 8-10 illustrate an exemplary embodiment of an oven 10 withreflective heat shields 810, 812 that reflect radiant heat (indicated byreference character 820) directed at the upper front corners 720 and therear upper corners 722. By reflecting the radiant heat 820 as indicatedby arrow 822, the heat shields 810, 812 reduce the temperature (andthereby eliminate hotspots) at the upper front corners 720 and the upperrear corners 722. The reflective heat shields 810, 812 can take a widevariety of different forms. For example, the reflective heat shields810, 812 can be a metallic foil, a metalized film, a reflective paint orother reflective coating and/or a polished interior surface of the outercabinet 33. The reflective heat shields 810, 812 can be made from anymaterial that reflects more radiant heat energy than the interiorsurfaces of the side panels 52 and 54 and a back panel 24 of the oven.In one exemplary embodiment, the emissivity of the reflective heatshields is greater than 0.1. When the reflective heat shields are madefrom a metallic foil, the metallic foil may be made from aluminum oranother material, such as for example a metalized film.

The reflective heat shields 810, 812 can be positioned to reflectradiant heat energy that would otherwise heat the upper front corners720 and the upper rear corners 722 in a wide variety of different ways.In the illustrated embodiment, the reflective heat shields 810, 812 areadhered to the upper front corners 720 and the upper rear corners 722 ofthe oven or the upper front corners 720 and/or the upper rear corners722 are coated with a material that forms the heat shields 810, 812. Inthe illustrated embodiment, the reflective heat shields are disposed onan inner surface 830 of the side panels 52, 54 and/or a bottom surface832 of the top panel 12. In another exemplary embodiment, the reflectiveheat shields 810, 812 are formed on upper corners 850, 852 of theinsulation material 38 to prevent radiant thermal energy from reachingthe upper front corners 720 and upper rear corners 722 and therebyprevent hotspots from occurring at these locations.

FIGS. 11A and 11B are schematic illustrations similar to FIGS. 7A and 7Bshowing thermal measurements taken during a test of an oven 10 havingthe heat shields 810, 812 in the test fixture 410 of FIGS. 4-6. As canbe seen from FIGS. 11A and 11B, the hot spots at upper front corners 720and at rear upper corners 722 of the oven during thermal testing in thefixture 410 are reduced or eliminated.

FIGS. 12-14 illustrate that when the insulation 38 is installed on theoven liner 15, one or more gaps 1210 may form between the insulation 38and the oven liner 15. For example, the insulation 38 may bunch up onthe opposing liner sides 15 a and 15 b, the liner top 15 c, the linerbottom 15 d and/or a liner back 15 e to form one or more gaps 1210. Whena gap 1210 is present, air in the gap 1210 is heated by the oven liner15, may flow out of the gap 38 as indicated by arrow 1250 (See FIGS. 13and 14), and heat an interior surface of the outer oven cabinet 33. Forexample, the heated air from the gap 1210 may heat an upper surface 1260of the back panel 24 and cause a hotspot at that location. However, theheated air from the gap 1210 may cause one or more hotspot at anylocation or locations of the outer oven cabinet 33.

FIG. 15 is a schematic illustration showing thermal measurements takenduring a test of the oven 10 with one or more gaps 1210 as shown inFIGS. 12-14 in the test fixture 410 of FIGS. 4-6. In FIG. 15, portion1510 represents thermal measurements of a right side of the oven 10,portion 1512 represents thermal measurements of the back panel 24, andportion 1514 represents thermal measurements of the left side of theoven 10. Shaded areas 1520 represent hot spots at the upper portion 1260of the back panel 24 having one or more gaps 1210 illustrated by FIGS.12-14 during thermal testing in the fixture 410.

FIG. 16 illustrates that when the insulation 38 is installed on the ovenliner 15, the insulation may contact the outer oven cabinet 33. Forexample, the insulation 38 may bunch up on the opposing liner sides 15 aand 15 b, the liner top 15 c, the liner bottom 15 d and/or a liner back15 e and come into contact with the outer oven cabinet 33. When theinsulation 38 contacts the outer oven cabinet 33, heat in the insulation38 is conducted directly into the cabinet 33. In the illustratedexample, the insulation 38 contacts the left side 52, causing heat inthe insulation 38 to be conducted into the left side panel 52 and aresulting hotspot at that location. However, the contact between theinsulation 38 and the cabinet 33 and resulting hotspot may be at anylocation of the outer oven cabinet 33.

FIG. 17 is a schematic illustration showing thermal measurements takenduring a test of the oven 10 with contact between the insulation 38 andthe left side 52 in the test fixture 410 of FIGS. 4-6. Shaded area 1720represents a hot spot in the middle of the left side panel 52.

FIGS. 18-20 illustrate an exemplary embodiment of an oven 10 with one ormore retainers 1810 that keep the insulation 38 in continuous contactwith the oven liner 15 such that no gaps 1210 (See FIGS. 12-14) areformed between the oven liner 15 and/or that prevent the insulation 38from contacting the outer cabinet 33. By eliminating the gaps 1210 andcontact between the insulation 38 and the outer cabinet 33, hotspots dueto air heated in the gap 1210 and contact between the insulation 38 andthe cabinet 33 are reduced or eliminated.

The retainers 1810 can take a wide variety of different forms. In theillustrated embodiment, the retainers 1810 are discrete clips providedon one or more of the opposing liner sides 15 a and 15 b, the liner top15 c, the liner bottom 15 d and the liner back 15 e. In the illustratedexample, one clip is attached to each of the opposing liner sides 15 aand 15 b, the liner top 15 c, the liner bottom 15 d and the liner back15 e. However, any number of clips can be provided on any of theopposing liner sides 15 a and 15 b, the liner top 15 c, the liner bottom15 d and the liner back 15 e. In some embodiments, no clips are providedat one or more of the opposing liner sides 15 a and 15 b, the liner top15 c, the liner bottom 15 d and the liner back 15 e. In anotherexemplary embodiment, the retainers 1810 are not connected to the liner15. For example, the retainers 1810 may be spacers mounted to one ormore of the pair of opposed side panels 52 and 54, the back panel 24,the bottom panel 25, and the front panel 32 that press the insulation 38against the liner 15. The retainers 1810 can take any form thateliminates the gaps 1210 and/or contact between the insulation 38 andthe outer cabinet

The retainers 1810 can be made from a wide variety of differentmaterials. In one exemplary embodiment, the retainers 1810 are made froma material having a low thermal conductivity. By making the retainersfrom a material with a low thermal conductivity, heat that is conductedfrom the liner 15, through the retainer 1810, and to the outside of theinsulation 38 is minimized. The retainers 1810 can be positioned in awide variety of different ways. In the illustrated examples, theretainers 1810 are oriented at angles over the face of the insulationwith a center of the retainer positioned over the center of theinsulation face. This orientation eliminates the gaps 1210 and contactbetween the insulation 38 and the housing 33. However, the retainers canbe positioned in a wide variety of different orientations than as shown.

FIGS. 21 and 22 are schematic illustrations similar to FIGS. 15 and 17showing thermal measurements taken during a test of an oven 10 havingthe retainers 1810 in the test fixture 410 of FIGS. 4-6. As can be seenfrom FIGS. 21 and 22, the hot spots at the upper portion 1520 of theback panel 24 and the hot spot in the middle of the left side panel 52during thermal testing in the fixture 410 are reduced or eliminated.

Referring now to FIGS. 23-25, there is illustrated an improved thermaloven 10. As will be explained in detail below, the thermal oven 10 ofthis exemplary embodiment includes a multiple layer insulation material2338. The multiple layer insulation material 2338 is positioned betweenouter surfaces 16 a, 16 b, 16 c, 16 d and 16 e of the opposing linersides, liner top, liner bottom, and liner back, 15 a, 15 b, 15 c, 15 dand 15 e and interior surfaces 52 a, 54 a, 25 a, 24 a and 12 a of theopposed side panels, back panel, bottom pane and cooking surface 52, 54,25, 24 and 12 respectively. In one embodiment, each of the layers of thefibrous insulation material 2338 is made of glass fibers. For example,the fibrous insulation material 2338 can be binderless and/or be heldtogether with dry binder as described above. Alternatively, the fibrousinsulation material 38 can be another insulation material, such as forexample mineral wool, rock wool, polymer fibers, sufficient to insulatethe oven cavity 16.

In the exemplary embodiment illustrated by FIGS. 23-25 the thermal oven10 has an inner insulation material 2338 a is positioned in contact withthe outside surfaces 16 a, 16 b, 16 c, 16 d and 16 e of the liner 15 andan outer insulation material 2338 b disposed around the inner insulationmaterial 2338 a. In an exemplary embodiment, the inner insulationmaterial 2338 a is a high density insulation and is configured toprovide a predetermined level of thermal insulation. Alternatively, theinner insulation material 2338 a can be any insulation sufficient toprovide a predetermined level of thermal insulation. The innerinsulation material 2338 a has a thickness t1. In one embodiment, thethickness t1 is in a range from about 0.50 inches (1.27 cm) to about 1.5inches (3.81 cm). In another embodiment, the thickness t1 can be lessthan 0.50 inches (1.27 cm) or more than 1.5 inches (3.81 cm). In oneembodiment, the inner insulation material 2338 a has a density in arange from about 1.0 lb/ft̂3 to about 15.0 lb/ft̂3. In another embodiment,the inner fibrous insulation material 2338 a can have a density lessthan 1.0 lb/ft̂3 or more than 15.0 lb/ft̂3.

In one exemplary embodiment, the outer insulation material layer 2338 bis low density insulation and is configured to replace a portion of theair gap 36 with a semi-transparent thermal insulation. This low density,semi-transparent outer insulation layer 2338 b prevents the high densitylayer 2338 b from contacting the outer housing and thereby prevents hotspots due to conduction from the high density layer 2338 b to thehousing 33. Alternatively, the outer insulation material 2338 b can bean insulation sufficient to provide thermal insulation. The outerinsulation material layer 2338 b has a thickness t2. In one embodiment,the thickness t2 is in a range from about 0.50 inches (1.27 cm) to about1.5 inches (3.81 cm). In another embodiment, the thickness t2 can beless than 0.50 inches (1.27 cm) or more than 1.5 inches (3.81 cm).

In the embodiment shown in FIGS. 23-25, the outer insulation material2338 b reduces convective heat transfer while having little of no effecton radiative heat transfer. The outer insulation material 2338 b istherefore typically a lower density than the inner insulation material2338 b. The outer insulation material 2338 a is also typically moretransparent to thermal radiation (in a range from about 0.1 micron toabout 100 micron wavelength) than the inner insulation material 2338 b.

Referring now to FIGS. 26-28, there is illustrated an improved thermaloven 10 that is similar to the embodiment illustrated by FIGS. 23-25,except the outer layer 2338 b entirely fills the gaps between the innerlayer 2338 a and one or more of the inside surfaces 52 a, 54 a, 25 a, 24a and 12 a of the opposed side panels, back panel, bottom pane andcooking surface 52, 54, 25, 24 and 12 respectively of the outer cabinet33. As in the embodiment illustrated by FIGS. 23-25, the innerinsulation material 2338 a is a high density insulation and isconfigured to provide a predetermined level of thermal insulation. Theinner insulation material 2338 a has a thickness t1. In one embodiment,the thickness t1 is in a range from about 0.50 inches (1.27 cm) to about1.5 inches (3.81 cm). In another embodiment, the thickness t1 can beless than 0.50 inches (1.27 cm) or more than 1.5 inches (3.81 cm). Inone embodiment, the inner insulation material 2338 a has a density in arange from about 1.0 lb/ft̂3 to about 15.0 lb/ft̂3. In another embodiment,the inner fibrous insulation material 2338 a can have a density lessthan 1.0 lb/ft̂3 or more than 15.0 lb/ft̂3.

As in the embodiment illustrated by FIGS. 23-25, the outer insulationmaterial layer 2338 b is low density insulation in the embodimentillustrated by FIGS. 26-28. However, in the example illustrated by FIGS.26-28 the outer insulation layer 2338 b is configured to replace theentire air gap 36 with a semi-transparent thermal insulation. This lowdensity, semi-transparent outer insulation layer 2338 b prevents thehigh density layer 2338 b from contacting the outer housing and therebyprevents hot spots due to conduction from the high density layer 2338 bto the housing 33. In the embodiment illustrated by FIGS. 26-28, theouter insulation material layer 2338 b has a thickness t3, which isequal to or slightly greater than the distance d3 between outsidesurface of the inner insulation layer 2338 a and the inside surface 52a, 54 a, 25 a, 24 a and 12 a of the opposed side panels, back panel,bottom pane and cooking surface 52, 54, 25, 24 and 12 respectively. Theouter layer of insulation material 2338 b need not contact all of theopposed side panels, back panel, bottom panel and cooking surface 52,54, 25, 24 and 12. In one exemplary embodiment, for the panels that arenot contacted, the outer insulation layer 2338 b has a thickness t2 isin a range from about 0.50 inches (1.27 cm) to about 1.5 inches (3.81cm). In another embodiment, the thickness t2 can be less than 0.50inches (1.27 cm) or more than 1.5 inches (3.81 cm).

FIGS. 29 and 30 illustrate an exemplary embodiment of a of a thermaloven 10 with convection airflow management features 2910. In theexemplary embodiment illustrated by FIGS. 29 and 30, the airflowmanagement features 2910 minimize outer surface temperatures by drawingair into a bottom portion 2912 of the outer cabinet 33 as indicated byarrows 2913, channeling that air through the gap 36 along the sides 52,54 and back 24 of the thermal oven 10 as indicated by arrows 2918, andout the back 24 of the oven as indicated by arrows 2920. Thiscontrolling of the convective airflow reduces the maximum temperature ofthe outer cabinet 33 below a maximum allowable outside surfacetemperature of the oven 10. In addition to providing strategicallylocated openings to the exterior, the air gap 38 spaces and channels areconfigured to manage the convective airflow.

In the example illustrated by FIGS. 29 and 30, air intake openings 2930are provided in the bottom wall and/or air intake openings 2932 areprovided in a lower portion of the rear wall. Air outlet openings 2940are provided in an upper portion of the rear wall. However, a widevariety of different intake and outlet configurations can be employed.In the example illustrated by FIGS. 29 and 30, gaps 36 are providedbetween the insulation 38 and the opposed side panels 52, 54 and betweenthe insulation 38 and the back panel 25. However, the gaps 36 can beprovided between the insulation 38 and any of the panels of the outercabinet 33. In an exemplary embodiment, the size of the gaps is selectedto keep the maximum temperature of the outer cabinet 33 below a maximumallowable outside surface temperature of the oven 10.

The thermal management features disclosed in this application can beused in a wide variety of different types and configurations of ovens10. The thermal management features have been generally described withreference to a conventional single oven. However, the thermal managementfeatures disclosed by this application can be used with any type ofoven, such as the double oven 3110 shown in FIGS. 31-33.

The double oven 3110 can take a wide variety of different forms. In theexample illustrated by FIGS. 31-33, the double oven 3110 includes asubstantially flat, top cooking surface 12. A plurality of heatingelements or burners 14 are typically positioned on the top cookingsurface 12, although the heating elements or burners 14 are optional.The double oven 3110 includes a plurality of controls 26 for the burners14 on the cooking surface as well as a control panel 28 for controllingthe temperatures within oven cavities 3116, 3117.

As shown in FIGS. 31-33, the double oven 3110 includes a pair of opposedside panels 52 and 54, a back panel 24, a bottom panel 25, and a frontpanel 32. The opposed side panels 52 and 54, back panel 24, bottom panel25, front panel 32 and cooking surface 12 are configured to form anouter oven cabinet 33.

The front panel 32 includes upper and lower insulated oven doors 3118,3119 pivotally connected to the front panel 32. The oven doors 3118,3119 are hinged at a lower end to the front panel 32 such that the ovendoors can be pivoted away from the front panel 32 and the oven cavities3116, 3117.

As shown in FIGS. 32 and 33, the outer oven cabinet 33 supports an upperinner oven liner 3115 and a lower inner oven liner 3113. The upper inneroven liner 3115 includes opposing liner sides 3115 a and 3115 b, a linertop 3115 c, a liner bottom 3115 d and a liner back 3115 e. The opposingliner sides 3115 a and 3115 b, liner top 3115 c, liner bottom 3115 d,liner back 3115 e and oven door 3118 are configured to define the upperoven cavity 3116. The lower inner oven liner 3113 includes opposingliner sides 3113 a and 3113 b, a liner top 3113 c, a liner bottom 3113 dand a liner back 3113 e. The opposing liner sides 3113 a and 3113 b,liner top 3113 c, liner bottom 3113 d, liner back 3113 e and oven door3119 are configured to define the lower oven cavity 3117.

As further shown in FIGS. 32 and 33, opposing liner sides 3115 a and3115 b, the liner top 3115 c, and a liner back 3115 e of the top ovenliner 3115 are covered by insulation material 3138. The lower oven lineris covered by insulation material 3139. A typical insulation material3138, 3139 is fiberglass insulation, although other insulation materialcan be used. In one exemplary embodiment, the insulation material 3138and/or 3139 is a binderless or dry binder fiberglass insulationmaterial. For example, the fiberglass insulation material may be any ofthe insulation materials and/or may be formed by any of the processesdescribed in U.S. patent application Ser. No. 13/632,895, titled “METHODFOR FORMING A WEB FROM FIBROUS MATERIAL,” filed on Oct. 1, 2013 and U.S.patent application Ser. No. 13/839,350, titled “METHOD FOR FORMING A WEBFROM FIBROUS MATERIAL,” filed on Mar. 15, 2013, and which is acontinuation-in-part of U.S. patent application Ser. No. 13/632,895,both of which are incorporated herein by reference in their entirety.

As shown in FIGS. 32 and 33, an air gap 36 is formed between theinsulation material 3138, 3139 and the outer oven cabinet 33. The airgap 36 is used as a further insulator to limit the conductive heattransfer between oven liners 3115, 3113 and the outer oven cabinet 33.The use of the air gap 36 supplements the insulation material 3138, 3139to minimize the surface temperatures on the outer surfaces of the outeroven cabinet 33.

During normal cooking operation, the double oven 3110 will heat the ovencavities 3116, 3117 to cooking temperature ranges from about 250.degree.F. (121.degree. C.) to about 500.degree. F. (260.degree. C.). Whenoperating in a self-cleaning mode, the double oven 3110 heats the ovencavities 3116, 3117 to temperatures in a range from about 750.degree. F.(398.degree. C.) to about 900.degree. F. (482.degree. C.). Heat exposuretests, such as the UL858 Standard for Household Electric Ranges and ANSIZ21.1 Standard for Household Cooking Gas Appliances, require that themaximum allowable surface temperature be 152.degree. F. for a paintedmetal surface, 160.degree. F. for a porcelain enamel surface, or172.degree. F. for a glass surface.

Referring to FIGS. 32 and 33, when the insulation 3138 is installed onthe oven liner 3115 and the insulation 3139 is installed on the ovenliner 3113, a gap 3210 is formed between the insulation 3139 and theoven liner 3115. Air in the gap 3210 is heated by the oven liner 3115,may flow out of the gap 3210 and/or be drawn into the gap as indicatedby arrow 3250, and heat an interior surface of the outer oven cabinet33. For example, the heated air from the gap 3210 may heat an uppersurface 1260 of the back panel 24 and cause a hotspot at that location.However, the heated air from the gap 3210 may cause one or more hotspotat any location or locations of the outer oven cabinet 33.

FIG. 34 is a schematic illustration showing thermal measurements takenduring a test of the double oven 3110 with a gap 3210 as shown in FIG.32-14 in the test fixture 410 of FIGS. 4-6. In FIG. 34, portion 3410represents thermal measurements of a right side of the oven 3110,portion 3412 represents thermal measurements of the back panel 24, andportion 3414 represents thermal measurements of the left side of theoven 3110. Shaded areas 3420 represent hot spots at an upper portion1530 of the back panel 24 an oven 3110 having the gaps 3410 illustratedby FIG. 34 during thermal testing in the fixture 410.

FIGS. 35 and 36 illustrate an exemplary embodiment of a double oven 3110having insulation 3138 with extensions 3510 that cover the sides 3512 ofthe insulation 3139. The extensions prevent or inhibit air from beingdrawn into the gap 3210 and/or out of the gap through an interface 3514(See FIGS. 32 and 33) between the sides 3512 of the insulation 3139 andsides 3612 of the insulation 3138. In an exemplary embodiment, the airgap 36 is maintained between the extensions 3510 and the cabinet 33 asshown in FIG. 35. In an alternate embodiment, the extensions 3510 may beconfigured to engage the cabinet, such that there is no gap 36. Bypreventing or inhibiting air from being drawn into the gap 3210 and/orout of the gap, hotspots due to air heated in the gap 3210 are reducedor eliminated.

Air can be prevented or inhibited from being drawn into the gap 3210and/or out of the gap through the interface 3514 between the sides 3512of the insulation 3139 and sides 3612 of the insulation 3138 in avariety of ways other than providing the extensions 3510. For example,the interface 3514 between the sides can be sealed and/or securedtogether, the gap 3210 can be filled, for example with additionalinsulation, and/or extensions of the lower insulation 3139 can extend upalong sides 3612 of the insulation 3138.

FIG. 37 is a schematic illustrations similar to FIG. 34 showing thermalmeasurements taken during a test of a double oven 10 where air isprevented or inhibited from being drawn into the gap 3210 and/or out ofthe gap through the interface 3514 in the test fixture 410 of FIGS. 4-6.For example, FIG. 7 is representative of a test of the double oven 3110illustrated by FIGS. 35 and 36. As can be seen from FIGS. 34 and 37, thehot spots at the upper portion 1530 of the back panel 24 during thermaltesting in the fixture 410 are reduced or eliminated.

FIGS. 38-40 illustrate an exemplary embodiment of an oven 10 with one ormore standoffs 1820 with retaining elements 1822 that keep theinsulation 38 in continuous contact with the oven liner 15 such that nogaps 1210 (See FIGS. 12-14) are formed between the oven liner 15 and/orthat prevent the insulation 38 from contacting the outer cabinet 33. Byeliminating the gaps 1210 and contact between the insulation 38 and theouter cabinet 33, hotspots due to air heated in the gap 1210 and contactbetween the insulation 38 and the cabinet 33 are reduced or eliminated.

The standoffs 1820 and retaining elements 1822 can take a wide varietyof different forms. In the illustrated embodiment, the standoffs 1820are posts provided at one or more of the sides of the outer cabinet 33.In the illustrated example, two posts are attached to each of theopposing side panels 52 and 54, the bottom panel 25, and the cookingsurface 12. However, any number of posts can be provided on any of theopposing side panels 52 and 54, the bottom panel 25, and the cookingsurface 12. In the illustrated embodiment, each pair of standoffs 1820on a side of the outer cabinet 33 are connected by a retaining element1822.

The standoffs 1820 can be made from a wide variety of differentmaterials. In one exemplary embodiment, the standoffs 1820 are made froma material having a low thermal conductivity. By making the retainersfrom a material with a low thermal conductivity, heat that is conductedfrom the outside of the insulation 38, through the standoff 1820, and tothe outer cabinet 33 is minimized. The standoffs 1820 can be positionedin a wide variety of different ways. In the illustrated examples, thestandoffs 1820 are positioned such that the retaining elements 1822connecting them are oriented at angles over the face of the insulationwith a center of the retaining element positioned over the center of theinsulation face. This orientation eliminates the gaps 1210 and contactbetween the insulation 38 and the outer cabinet 33. However, thestandoffs and retaining elements can be positioned in a wide variety ofdifferent orientations than as shown.

The retaining elements 1822 can be made from a wide variety of differentmaterials. In one exemplary embodiment, the retaining elements 1822 aremade from stiff metal wire. In the illustrated example the metal wireforms a straight line between the two posts it is connected to. However,the retaining element may be formed into a wide variety of differentshapes than as shown. For example, the retaining elements may be bentwire or other material, such that the retaining elements 1822 have pointcontact at a plurality of locations, rather than the continuous contactof a straight, elongated retaining element. For example, the wire mayhave a zig-zag shape similar to the shape of the ends of the standoffs1830 illustrated by FIG. 41 and described below.

FIGS. 41-43 illustrate an exemplary embodiment of an oven 10 with one ormore “M” or “W” shaped standoffs 1830 that keep the insulation 38 incontinuous contact with the oven liner 15 such that no gaps 1210 (SeeFIGS. 12-14) are formed between the oven liner 15 and/or that preventthe insulation 38 from contacting the outer cabinet 33. By eliminatingthe gaps 1210 and contact between the insulation 38 and the outercabinet 33, hotspots due to air heated in the gap 1210 and contactbetween the insulation 38 and the cabinet 33 are reduced or eliminated.The standoffs 1830 may be attached to the outer cabinet 33 of the oven10 or the insulation 38.

The standoffs 1830 can be made from a wide variety of differentmaterials. In one exemplary embodiment, the standoffs 1830 are made froma material having a low thermal conductivity. By making the retainersfrom a material with a low thermal conductivity, heat that is conductedfrom the outside of the insulation 38, through the standoff 1830, and tothe outer cabinet 33 is minimized. In the illustrated example, thestandoffs 1830 are formed into an “M” or “W” shape, but the standoffs1830 may be formed in a wide variety of different shapes than as shown.

The standoffs 1830 can be positioned in a wide variety of differentways. In the illustrated example, two standoffs 1830 are positioned oneach of the opposing side panels 52 and 54, the bottom panel 25, and thecooking surface 12. The standoffs 1830 are shown positioned near thecorner of the face of the insulation 38 that they are in contact with.However, any number of standoffs 1830 may be provided in any arrangementon each face of the outer cabinet 13.

FIG. 44 illustrates an exemplary embodiment of an oven 10 with one ormore “M” or “W” shaped standoffs 1840 that keep the insulation 38 incontinuous contact with the oven liner 15 such that no gaps 1210 (SeeFIGS. 12-14) are formed between the oven liner 15 and/or that preventthe insulation 38 from contacting the outer cabinet 33. By eliminatingthe gaps 1210 and contact between the insulation 38 and the outercabinet 33, hotspots due to air heated in the gap 1210 and contactbetween the insulation 38 and the cabinet 33 are reduced or eliminated.The standoffs 1840 are attached to the liner 15 and pass through theinsulation 38 to press against the outer cabinet 33 and against theinsulation 38.

The standoffs 1840 can be made from a wide variety of differentmaterials. In one exemplary embodiment, the standoffs 1840 are made froma material having a low thermal conductivity. By making the retainersfrom a material with a low thermal conductivity, heat that is conductedfrom the liner 15, through the standoff 1840, and to the outer cabinet33 is minimized. In the illustrated example, the standoffs 1840 areformed into an “M” or “W” shape, but the standoffs 1840 may be formed ina wide variety of different shapes than as shown.

The standoffs 1840 can be positioned in a wide variety of differentways. In the illustrated example, two standoffs 1840 are positioned oneach of the opposing liner sides 15 a and 15 b, the liner top 15 c, andthe liner bottom 15 d. The standoffs 1840 are shown positioned near thecorner of each of the liner sides that they are attached to. However,any number of standoffs 1840 may be provided in any arrangement on eachface of the liner 15.

The present application discloses several different embodiments ofthermal appliances, such as ovens 10, with features that keep themaximum temperature of the outer cabinet 33 below a maximum allowableoutside surface temperature of the oven 10. Any of the features of anyof the embodiments disclosed in this application can be combined withany of the features of any of the other embodiments disclosed by thisapplication. Additional exemplary embodiments of the present applicationcomprise combinations and subcombinations of the features of theexemplary embodiments described above.

1-28. (canceled)
 29. A thermal appliance comprising: an enclosure thatincludes an inner surface and an outer surface, wherein the innersurface has a top, a bottom, a back, a front, a first side, and a secondside; a heating compartment within the enclosure, the heatingcompartment having an inner surface and an outer surface; insulatingmaterial disposed between the outer surface of the heating compartmentand the inner surface of the enclosure; two or more standoffs attachedto the enclosure that are configured to prevent air gaps from formingbetween the insulating material and the outer surface of the heatingcompartment and to prevent the insulating material from touching theinner surface of the enclosure, wherein the one or more standoffsinclude a first standoff connected to the first side of the enclosure ata first location and a second standoff connected to the first side ofthe enclosure at a second location.
 30. The thermal appliance of claim29, wherein the one or more standoffs are posts.
 31. The thermalappliance of claim 29, wherein the one or more standoffs are metal wiresbent into a “W” or a “M” shape.
 32. The thermal appliance of claim 29,wherein only the first standoff and the second standoff are attached tothe first side of the enclosure.
 33. The thermal appliance of claim 29,wherein the first location is closer to the front and the top of theinner surface of the enclosure relative to the back and the bottom, andwherein the second location is closer to the back and the bottom of theinner surface of the enclosure relative to the front and the top. 34.The thermal appliance of claim 29, wherein the first location is closerto the front and the bottom of the inner surface of the enclosurerelative to the back and the top, and wherein the second location iscloser to the back and the top of the inner surface of the enclosurerelative to the front and the bottom.
 35. The thermal appliance of claim29, wherein the first side of the inner surface of the enclosure has atop edge, a bottom edge, and two opposing side edges; wherein an axisextends through the first location and the second location; and whereinthe axis is not perpendicular to the top edge, the bottom edge, and thetwo opposing side edges.
 36. The thermal appliance of claim 29, whereinthe first standoff and the second standoff are connected by a retainingelement.
 37. The thermal appliance of claim 36, wherein the retainingelement is a metal wire.
 38. The thermal appliance of claim 29, whereinthe one or more standoffs are made from an insulating material.
 39. Athermal appliance comprising: an enclosure that includes an innersurface and an outer surface, wherein the inner surface has a top, abottom, a back, a front, a first side, and a second side; a heatingcompartment within the enclosure, the heating compartment having aninner surface and an outer surface; insulating material disposed betweenthe outer surface of the heating compartment and the inner surface ofthe enclosure; two or more standoffs attached to each of the top, thebottom, the first side, and the second side of the inner surface of theenclosure; wherein the standoffs are configured to prevent air gaps fromforming between the insulating material and the outer surface of theheating compartment and to prevent the insulating material from touchingthe inner surface of the enclosure.
 40. The thermal appliance of claim39, wherein the standoffs are posts.
 41. The thermal appliance of claim39, wherein the standoffs are metal wires bent into a “W” or a “M”shape.
 42. The thermal appliance of claim 39, wherein only two standoffsare attached to at least one of the top, the bottom, the first side, andthe second side of the inner surface of the enclosure; and wherein thetwo standoffs include a first standoff attached to a first location anda second standoff attached to a second location.
 43. The thermalappliance of claim 42, wherein the each of the top, the bottom, thefirst side, and the second side of the inner surface of the enclosurehas a top edge, a bottom edge, and two opposing side edges; wherein anaxis extends through the first location and a second location; andwherein the axis is not perpendicular to the top edge, the bottom edge,and the two opposing side edges.
 44. The thermal appliance of claim 39,wherein the first standoff and the second standoff are connected by aretaining element.
 45. The thermal appliance of claim 44, wherein theretaining element is a metal wire.
 46. The thermal appliance of claim39, wherein the one or more standoffs are made from an insulatingmaterial.
 47. A thermal appliance comprising: an enclosure that includesan inner surface and an outer surface, wherein the inner surface has atop, a bottom, a back, a front, a first side, and a second side; aheating compartment within the enclosure, the heating compartment havingan inner surface and an outer surface; insulating material disposedbetween the outer surface of the heating compartment and the innersurface of the enclosure such that an air gap is provided adjacent to abottom surface of the insulating material; one or more standoffsattached to the inner surface of the enclosure that are configured toprevent air gaps from forming between the insulating material and theouter surface of the heating compartment and to prevent the insulatingmaterial from touching the inner surface of the enclosure.
 48. Thethermal appliance of claim 47, wherein the one or more standoffs includea first standoff connected to the bottom of the inner surface of theenclosure at a first location and a second standoff connected to thebottom of the inner surface of the enclosure at a second location. 49.The thermal appliance of claim 48, wherein the first location is closerto the front and the first side of the inner surface of the enclosurerelative to the back and the second side, and wherein the secondlocation is closer to the back and the second side of the inner surfaceof the enclosure relative to the front and the first side.
 50. Thethermal appliance of claim 48, wherein the bottom of the inner surfaceof the enclosure has a top edge, a bottom edge, and two opposing sideedges; wherein an axis extends through the first location and the secondlocation; and wherein the axis is not perpendicular to the top edge, thebottom edge, and the two opposing side edges.
 51. The thermal applianceof claim 48, wherein the first standoff and the second standoff areconnected by a retaining element.
 52. The thermal appliance of claim 51,wherein the retaining element is a metal wire.
 53. The thermal applianceof claim 47, wherein the one or more standoffs are posts.
 54. Thethermal appliance of claim 47, wherein the one or more standoffs aremetal wires bent into a “W” or a “M” shape.
 55. The thermal appliance ofclaim 47, wherein the one or more standoffs are made from an insulatingmaterial.